1. Field of the Invention
The present invention relates to a copying machine in which the original base line defining the area to be copied can be selected as desired for a document placed on the original table. 2. Description of the Prior Art
Copying machine hitherto known in the art includes an original table having a surface on which a document to be copied is placed. The table surface on which an original is placed (hereinafter referred to as original placement surface) is usually a rectangular or cylindrical surface of a size large enough to cover the largest size of original and has an original base line along which a document to be copied should be positioned.
FIG. 1A shows an example of rectangular original placement surface with two opposite long sides extending in X-direction and two opposite short sides extending in Y-direction normal to the X-direction. When a document of format A3 (size: 420.times.297 m/m) or of format B5 (182.times.257 m/m) is placed on the surface, the long and short sides of the rectangular original placement surface provide an original base line along which the document to be copied should be placed respectively. In this case, the sides of the rectangular original surface constitute the above mentioned original base line.
FIG. 1B shows another case of original alignment on the rectangular original placement surface. In this case, the center line of a document of format A3 or of format A4 (210.times.297 m/m) is aligned with the center line Yo of the rectangular original placement surface and one short side of the document is aligned with the corresponding one short side of the original placement surface as shown in FIG. 1B. Therefore, the short side of the rectangle provides an original base line for alignment in X-direction and the center line Yo means a base for alignment in Y-direction.
Herein, the term "original" should be understood to include not only a normal sheet of document or book but also a portion or portions thereof to be copied and a plural number of small size documents placed on the original placement surface at the same time for making copies thereof separately.
In the known copying machine, the above described original base line is located in a fixed position and therefore no change of the position is allowable. Since, as previously noted, a pair of original base lines in X and Y directions define one position in which one original should be placed, only one original which can be placed on the original placement surface for each copying operation.
However, the original placement surface has an area large enough to cover an original of the largest format, for example, format A3. If the size of original to be copied is of a smaller format such as A4, A5 (210.times.148 m/m) or A6 (148.times.105 m/m), a plural number of such small size originals can be placed on the original placement surface at the same time. Also, if the original base line for copying could be determined as desired after placing a document on the original placement surface, there would be obtained such possibility that a plural number of areas of one document placed on the original placement surface can be copied separately without the necessity of moving the document every time. This would give a great convenience, for example, for such case where two pages of a bound document or book placed opened on the original placement surface are copied separately.
As will be understood by the above mentioned examples, copying machines could have an additional function very convenient to the users if it were made possible to selectively set the original base line in both of X and Y directions as desired for a plural number of originals placed on the original placement surface at the same time for making copies thereof separately.
Another thing to be noted in connection with the present invention is that the area of the portion of a document to be copied does not always correspond to the size of copy material used at that time and there are often the cases where the area to be copied is smaller than the size of the copy material used. In such case, the copy produced from the original inevitably contains unnecessary image and information of portions other than the area to be copied (such as an image of the cover plate for original), since the image formed on the copy material generally covers whole the size of the material.
To eliminate this inconvenience, it is required to erase the unnecessary information so that the area to be copied may be exclusively copied on the copy material. If the copying machine were provided with means for determining a rectangular area on the copy material corresponding to the area of a document to be copied and preventing any unnecessary image from being formed on the remaining areas other than the determined rectangular area of the copy material, then the requirement could be satisfied and thereby the original processing ability of the copying machine might be further improved.